[OmniOS-discuss] 4kn or 512e with ashift=12

[Hanno Hirschberger]

On 21.03.2016 08:00, Fred Liu wrote:
> So that means illumos can handle 512n and 4kn automatically and properly?

Not necessarily as far as I know. Sometime drives are emulating 512 
blocks and don't properly tell the OS about that and Illumos ZFS is 
aligning the drives with ashift=9 which leads to enormous performance 
issues. Also forcing the system to handle drives with a specific sector 
size with the sd.conf doesn't turn out to be reliable in some cases (at 
least on my workstations). Here's what I do to ensure ashift=12 values:

Reboot the system with a Linux live disk of your choice and install ZoL 
in the live session. Then create the ZFS pool, export it and reboot the 
machine. OmniOS / Illumos can import the new pool without problems and 
the ashift value is correctly set. There was a fixed zpool binary 
(Solaris 11 binary) flying around the internet which can handle the "-o 
shift=12" parameter and works with OmniOS but unfortunately I can't find 
it again right now. This would make the reboot into a live session obsolete.

Does anyone know if the "ashift" parameter will be implemented in the 
OmniOS / Illumos zpool binary in the near future?

Best regards

Hanno